The Vasculature Flashcards
layers of blood vessels from innermost to outermost
- tunica interna
- tunica media
- tunica externa
what blood vessel layer is composed mostly of smooth muscle and is the primary site of inflammatory injury?
Tunica media
T/F: the tunica interna is a single layer of endothelial cells that is continuous from the heart?
TRUE
T/F: the arterial side acts as a blood reservoir
FALSE the venous side does, ~50% of blood is maintained in veins during relaxation
what are varicose veins?
failure of the valves in the veins, allowing blood to go backward in veins
Organs that receive a constant blood flow
- Brain (always)
- Kidney & Liver (not constant but more than other organs)
What determines blood flow (F)?
the pressure difference and the resistance to flow
what determines the resistance to flow?
largely determined by the radius of the conducting tube
T/F: small changes in radius bring about large changes in blood flow?
TRUE
T/F: increasing pressure or vessel radius can increase flow
TRUE
define compliance
how easily a structure stretches to accommodate a change in volume
Compliance = ____
∆Volume/∆Pressure
effect of fibrosis on lung compliance
decreases compliance, fibrosis hardens the tissues with scars
As blood volume increases what happens to BP and blood flow?
BP and flow increases
What is Hypovolemia?
low blood volume (bleeding, dehydration, vomiting)
T/F: 10-20% loss of blood volume can be physiologically compensated for
TRUE
what is pulse pressure?
systolic - diastolic pressure
how to calculate MAP
diastolic BP + 1/3 pulse pressure
T/F: BP is a clinical measure of tissue perfusion?
FALSE, MAP is
define MAP
the average pressure in the arteries during one cardiac cycle
what does MAP tell us?
tissue perfusion, how much blood moves through the organs
decreasing MAP suggests what?
blood flow has decreased
how is MAP related to TPR?
MAP = CO * TPR
(as well as diastolic + 1/3(pulse pressure)
If there is a decrease in CO how is MAP maintained?
increase TPR
sympathetic release of NE effect on arterioles
vasoconstriction of smooth muscle in vasculature
what controls the whole body blood flow?
Sympathetic NS
how are discrete tissue needs met?
local control factors monitor local blood flow
define reactive hyperemia
the transient increase in organ blood flow that occurs following a brief period of ischemia
Define acute/active hyperemia
increased blood flow associated with increased metabolic demand
Acute/active hyperemia is a result from _______ control factors?
Intrinsic –> increased metabolism of cells results in chemical changes in the ECF that act locally upon the arteriole smooth muscle causing it to relax which lowers the resistance of that arteriole and results in greater blood flow to that region
what helps pull fluid from interstitial spaces?
oncotic/colloid osmotic pressure
function of lymph nodes
clean out toxins from the fluid before being returned to blood vessels
flow rate is directly proportional to ________
pressure difference between 2 points
flow rate is inversely proportional to _________
resistance
what are the determinants of resistance?
- viscosity of the fluid
- length of the tube through which fluid is flowing
- radius of the tube through which fluid is flowing
what is the most important determinant of resistance to flow in blood vessels?
radius of the vessel
resistance is inversely proportional to ________
the radius of the vessel
resistance is directly proportional to ________
both the fluid viscosity and the vessel length
what increases blood viscosity?
increases in hematocirt
T/F: under most physiological conditions the viscosity of blood is relatively constant
TRUE
T/F: capillaries consist of only one layer?
TRUE, it is endothelium
what are the most important factors determing the magnitude of the pulse pressure?
- SV
- speed of ejection of the stroke volume
- arterial compliance
what pathophysioloy can impact the compliance of the arteries?
arteriosclerosis
what distinguishes active hyperemia from autoregulation?
the event that brings the mechanism to play
T/F: blood velocity is not dependent on the proximity to the heart, but rather on total cross-sectional area of the vessel type
TRUE
what are the 3 types of capillaries?
- Continuous
- Fenestrated
- Discontinuous
compare the “leakiness” of capillaries in the brain to that in the liver
the brain has very “tight” capillaries (continous) whereas the liver has larger “leakier” capillaries (discontinous)
what type of vessel offers the most resistance to flow?
Arterioles, which can VC or VD to change their radius and thus their resistance
how does constriction of veins impact flow?
increases forward flow back to the heart
what is the function of the arteriolar side of circulation?
- serves as low resistance system to allow easy movement of blood to various organs
- works as a “pressure reservoir” for mainting blood flow
What are the two types of arteries?
- Muscular
- Elastic
Where are elastic arteries?
closer to heart, allows for stretch/recoil
where are muscular arteries?
further from the heart.
Have more smooth muscle –> can alter diameter
Edema can result from ______
- high arterial BP
- venous obstruction
- increased interstitial protein concentration
- decreased plasma protein concentration
- obstruction to lymphatic drainage
describe the pressure in the lymphatic system
very low pressure system
